Department of Defense (DoD) platforms and structures operate under more rigorous requirements. Consequently, harsh environmental conditions in combat zones and aging fleets are of paramount concern and require discovery and manufacturing of advanced materials with optimized physical and mechanical properties. Advanced engineering materials, such as nanocrystalline (NC) metals and ceramics often have enhanced mechanical properties (high strength, increased wear resistance) compared to coarse-grained (CG) materials and hence are very attractive from an engineering perspective. However, to date, one difficulty in interpreting the results and drawing general conclusions from literature on the deformation and failure mechanisms of these advanced engineering materials is the lack of consistency between the experimental conditions from all these studies (material, specimen geometry, testing conditions, microstructure distribution, texture, GB character, impurity level, environment, etc.). Furthermore, there have been remarkably few systematic studies exploring how the interplay between microstructural (grain size and associated heterogeneities) and interfacially segregating solutes influences the stability of bulk NC metals and ceramics along with the associated deformation mechanics under dynamic (various stress states, i.e., varying stress triaxiality) and high temperature conditions (e.g. strain rate sensitivity at elevated temperatures). This proposal aims to address this knowledge gap through a synergistic combination of novel high strain rate testing setup, atomistic modeling, and transmission electron microscopy (TEM). For example with NC Cu-Ta as a model material system, this proposal aim to discover the role of process-induced microstructure and associate heterogeneity on deformation mechanisms under high temperature and complex dynamic strain rate conditions. Furthermore, from the Armys perspective, new advanced engineering materials, such as NC Cu-Ta have shown to meet or exceed properties as compared to CG Cu-Be alloys, which are hazardous materials shown to cause various health related issues.
|Effective start/end date||4/11/15 → 4/10/19|
- US Department of Defense (DOD): $375,000.00
Aging of materials
Transmission electron microscopy